The CDC states that lead poisoning is the number one environmental health problem, affecting children in the US because it affects one of every six at-risk children and it is acknowledged to be a source of cognitive and behavioral impairment. Only 25% of the at-risk US children are tested. Atomic absorption instruments do 80% of blood lead tests in the US, but this technology is not likely to become substantially more accessible because it is limited to sophisticated labs and requires skilled operators. The objective of this proposed multi-phase project is to develop an innovative "one-step" electrochemical blood lead testing technology that will satisfy the economic, performance, and logistical needs of at-risk populations. As shown feasible in Phase I work, we will configure a sensor that will accept an unmeasured, untreated sample and an assay that will produce a quantitative blood lead result in about 3 minutes. The market-need for a one-step, CLIA waived blood lead system will increase the amount of lead testing done and ultimately lower the cost per result to < $3. We will also work to improve electrochemical blood lead analysis performance and extend the dynamic response range to meet U.S. and worldwide needs. We will incorporate instrument and sensor features that would allow users to test unmeasured and untreated whole blood and obtain an accurate, precise result. The expected result of the overall project will be technology that will allow substantially more lead testing in the United States and worldwide. Within the guidelines of permissible levels of childhood blood lead levels there are as many as 10 million children at risk, but only 2.5 million are tested. Expensive atomic absorption instruments do 2 million of these tests at a cost of $1 to $3 per reportable result. Much less expensive instruments are used for point of- care electrochemical tests but presently cost $4 to $6 per reportable result. Atomic absorption cannot easily increase the number of blood lead tests done because it is logistically inaccessible to 80% of the US target population and nearly 100% of the target international population. The genuine potential in the US blood lead market (7.5 million tests) lies with cost-effective and rapid electrochemical measurement. The proposed high-performance, low-cost electrochemical technology will be extremely competitive for the $7.5 million available US market and the potentially much larger international market.